Non-aromatic chromophores for use in polymer anti-reflective coatings

ABSTRACT

An improved light attenuating compound for use in the production of microdevices is provided. Broadly, the light attenuating compound is non-aromatic and can be directly incorporated (either physically or chemically) into photolithographic compositions such as bottom anti-reflective coatings (BARC) and contact or via hole fill materials. The preferred non-aromatic compounds of the invention are conjugated aliphatic and alicyclic compounds which greatly enhance the plasma etch rate of the composition. Furthermore, the light attenuating compounds are useful for absorbing light at shorter wavelengths. In one embodiment, the inventive compounds can be polymerized so as to serve as both the polymer binder of the composition as well as the light absorbing constituent.

RELATED APPLICATION

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/450,966 filed Nov. 30, 1999, incorporated by referenceherein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention is broadly concerned with light attenuatingcompounds for incorporation into photolithographic compositions (e.g.,anti-reflective coatings and contact or via hole fill compositions)utilized in the manufacturing of microdevices. More particularly, thelight attenuating compounds are non-aromatic and are especially usefulfor absorbing light at shorter wavelengths (e.g., 248 nm). The compoundscan be physically incorporated into the particular composition, oralternately, can be chemically bonded to a polymer binder alreadypresent in the composition. The compounds of the invention compriseconjugated aliphatic and alicyclic moieties which meet the necessarylight absorbency requirements for the composition while enhancing theplasma etch rate of the composition when compared to prior art aromaticdyes.

[0004] 2. Description of the Prior Art

[0005] A frequent problem encountered by photoresists during themanufacturing of semiconductor devices is that activating radiation isreflected back into the photoresist by the substrate on which it issupported. Such reflectivity tends to cause blurred patterns whichdegrade the resolution of the photoresist. Degradation of the image inthe processed photoresist is particularly problematic when the substrateis non-planar and/or highly reflective. One approach to address thisproblem is the incorporation of an anti-reflective dye either into thephotoresist layer, into a contact or via hole fill composition, into abottom anti-reflective coating (BARC), or as a separate layer adjacentthe photoresist layer.

[0006] Prior art BARC compositions usually contain aromaticanti-reflective dyes which attenuate light that would otherwise reflectfrom the substrate during photoresist exposure. For example, anthraceneand naphthalene derivatives are typically the preferred dyes for use at248 nm exposing wavelengths. Dyes comprising a benzene ring with atleast one conjugated substituent are widely used in BARC's which operateat 365 nm, while dyes comprising a benzene ring without conjugatedsubstituents have ample absorptivity to satisfy most 193 nmapplications.

[0007] Aromatic dyes have been preferred for BARC applications becauseof their high light absorbency per unit mass as well as their wideavailability, easy preparation, and high chemical stability. Whilearomatic dyes are useful for achieving high film optical density, theylimit the plasma etch rate of the BARC compositions by virtue of theirchemical stability. Aromatic dyes require considerably more energy fordecomposition than do the polymer binders (which are typicallynon-aromatic) used in the BARC compositions. As a result, the compositeetch rate is highly dependent on the aromatic character of the dyes.

[0008] U.S. Pat. No. 4,719,166 to Blevins et al. discloses the use ofcertain butadienyl dyes in a photoresist layer, an anti-reflectivelayer, or a planarizing layer for do protecting photoresist elementsagainst reflection of activating radiation from the substrate. However,the dyes of the '166 patent are not attached to the backbone of apolymer binder, thus permitting them to readily solubilize in thephotoresist, often leading to pattern degradation. Furthermore, currenttechnology continues to require increasingly complex circuitry beimprinted on chips of decreasing size. These smaller chips requireshorter wavelengths (e.g., 248 nm) be used during photoresist exposure.The dyes of the '166 patent are useful for absorbing light only at 365nm exposure wavelengths, making them unsuitable for use in themanufacturing of most current microdevices.

[0009] There is a need for a compound which can effectively attenuatelight at shorter wavelengths and which does not inhibit the etch rate ofthe particular BARC or contact or via hole fill composition in which itis utilized.

SUMMARY OF THE INVENTION

[0010] The present invention fills this need by providing lightattenuating compounds for BARC compositions, contact or via hole fillcompositions, and other microdevice manufacturing compositions which donot inhibit the etch rate of the composition. Furthermore, the inventivecompounds are useful for absorbing light at shorter wavelengths.

[0011] In more detail, the light attenuating compounds are non-aromaticand can be formulated to absorb light at the desired wavelength.Advantageously, the compounds are also useful for absorbing light atwavelengths of less than about 300 nm, and preferably less than about250 nm (e.g., for 248 nm applications).

[0012] As used herein, non-aromatic refers to compounds or moieties ofcompounds which either:

[0013] (1) do not include a benzene ring; or

[0014] (2)

[0015] (a) have non-planar carbon skeletons; and

[0016] (b) do not contain (4n+2) π electrons, where n=0, 1, 2, 3, etc.(i.e., do not obey Hückel's Rule as described in Solomons, T. W.

[0017] Graham, Fundamentals of Organic Chemistry, 3rd ed., John Wiley &Sons, Inc. (1990)).

[0018] The light attenuating compounds of the invention comprisemoieties having general structural formulas (set forth in detail below).Preferably, these compounds include one or more reactive groups selectedfrom the group consisting of COOH, OH, CONH₂, CONHR, CH₂X groups, andmixtures thereof, where R is selected from the group consisting ofhydrogen, alkyls (preferably C₁-C₄ branched and unbranched), andheteroalkyls, and X is a halogen.

[0019] The light attenuating compounds can be incorporated into theparticular photolithographic composition either physically (i.e., as amixture) or by chemically attaching the light attenuating compound tothe polymer binder or resin present in the composition (either to afunctional group on the binder or directly to the backbone of thebinder). In situations where the light attenuating compound is attachedto the polymer binder, a linkage unit can be used as an intermediate forsecuring the light attenuating compound to the binder. That is, thelight attenuating compound can be attached to a linkage unit which inturn is attached to the polymer binder (either to a functional group onthe binder or to the binder backbone). Examples of suitable linkageunits are those which comprise a moiety selected from the groupconsisting of alkyls (preferably C₁-C₄ branched and unbranched), acyclicheteroalkyls, non-aromatic cyclic alkyls (preferably C₃-C₆) andnon-aromatic cyclic heteroalkyls.

[0020] In another embodiment, the light attenuating compounds can bepolymerized alone so as to directly form the polymer binder utilized inthe particular photolithographic composition while simultaneously actingas a light absorber. Thus, in these applications an additional polymerbinder would not be necessary.

[0021] In applications where a polymer binder other than the lightattenuating compound is present in the composition, the binder should bedissolved in a solvent system (either single or multiple solvents). Theparticular polymer binders and solvent systems utilized are readilyascertainable by those skilled in the art. Examples of suitable polymerbinders include polyesters, polyacrylates, polyheterocyclics,polyetherketones, polyhydroxystyrene, polycarbonates,polyepichlorohydrin, polyvinyl alcohol, oligomeric resins (such as crownethers, cyclodextrins, epoxy resins), and mixtures of the foregoing.Examples of preferred solvents for use in the solvent system includealcohols, ethers, glycol ethers, amides, esters, ketones, water,propylene glycol monomethyl ether (PGME), propylene glycol monomethylether acetate (PGMEA), ethyl lactate, and PCBTF(p-chlorobenzotrifluoride).

[0022] Incorporating light attenuating compounds into photolithographiccompositions in accordance with the invention will not increase the etchrate of the composition as is the case with prior art compositionscomprising aromatic dyes. Thus, when practicing the instant invention,the etch rate of the photolithographic composition will be at leastabout 4000 Å/minute, where a mixture of HBr and O₂ is the etchant gas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] While the inventive light attenuating compounds broadly includenon-aromatic dyes, and particularly non-aromatic dyes which absorb lightat shorter wavelengths, in preferred embodiments the compounds includeone or more of the following moieties.

[0024] Generally speaking, the light attenuating compounds shouldinclude at least one double bond in conjugation with at least oneelectron-withdrawing group (EWG). One such structure is shown below inFormula I.

[0025] where:

[0026] each R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl;

[0027] in structure A, where EWG and R₂ do not form a cyclic unit:

[0028] EWG is a non-aromatic electron-withdrawing group such as acarbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group; and

[0029] R₂ is non-aromatic and may be hydrogen, an acyclic (preferablyC₁-C₄ branched or unbranched) or cyclic (preferably C₅-C₆) alkyl orheteroalkyl, or an electron-withdrawing group such as a carbonyl, imino,cyano, carboxylic acid, carboxylic ester, carboxamido, carboximido, orsulfonyl group;

[0030] in structure B, where EWG and R₂ form a cyclicelectron-withdrawing unit, the cyclic unit preferably comprises a C═O,C═S, or a C═N at a first carbon atom, and: a C═O or a C═N attached to acarbon atom at least two carbon atoms away from the first carbon atom;or an O, S, or N as a member of the ring at least two positions awayfrom the first carbon atom; and

[0031] (1) and (2) refer to the respective double-bonded carbon atoms.

[0032] Examples of particularly preferred structures B of Formula Iwhere EWG and R₂ form a cyclic electron-withdrawing unit include thefollowing:

[0033] where R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl.

[0034] In another embodiment, the light attenuating compounds include atleast one EWG across a double bond from an electron donating group (EDG)as shown in Formula II.

[0035] Formula II:

[0036] where:

[0037] R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₁-C₆) alkyl or heteroalkyl;

[0038] EDG is an electron-donating group such as H₃CO—, —OH, orR_(x)R_(y)N—, where each of R_(x) and R_(y) is non-aromatic and mayindividually be hydrogen, or an acyclic (preferably C₁-C₂) or cyclic(preferably C₅-C₆) alkyl or heteroalkyl;

[0039] in structure A, where EWG and R₂ do not form a cyclic unit:

[0040] EWG is a non-aromatic electron-withdrawing group such as acarbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group; and

[0041] R₂ is non-aromatic and may be hydrogen, an acyclic (preferablyC₁-C₄ branched or unbranched) or cyclic (preferably C₅-C₆) alkyl orheteroalkyl, or an electron-withdrawing group such as a carbonyl, imino,cyano, carboxylic acid, carboxylic ester, carboxamido, carboximido, orsulfonyl group;

[0042] in structure B, where EWG and R₂ form a cyclicelectron-withdrawing unit, the cyclic unit preferably comprises a C═O,C═S, or a C═N at a first carbon atom, and: a C═O or a C═N attached to acarbon atom at least two carbon atoms away from the first carbon atom;or an O, S, or N as a member of the ring at least two positions awayfrom the first carbon atom; and

[0043] (1) and (2) refer to the respective double-bonded carbon atoms.

[0044] Examples of particularly preferred structures B of Formula IIwhere EWG and R₂ form a cyclic electron-withdrawing unit include thefollowing:

[0045] where R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl.

[0046] In another embodiment, the light attenuating compounds includetwo conjugated double bonds in series with at least one EWG (see FormulaIII) or with two EWG's (see Formula IV). The structures shown inFormulas III and IV are particularly useful at 248 nm or 365 nmwavelength applications, depending upon the selection of R and EWG.

[0047] Formula III:

[0048] where:

[0049] each R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl;

[0050] in structure A, where EWG and R₂ do not form a cyclic unit:

[0051] EWG is a non-aromatic electron-withdrawing group such as acarbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group; and

[0052] R₂ is non-aromatic and may be hydrogen, an acyclic (preferablyC₁-C₄ branched or unbranched) or cyclic (preferably C₅-C₆) alkyl orheteroalkyl, or an electron-withdrawing group such as a carbonyl, imino,cyano, carboxylic acid, carboxylic ester, carboxamido, carboximido, orsulfonyl group;

[0053] in structure B, where EWG and R₂ form a cyclicelectron-withdrawing unit, the cyclic unit preferably comprises a C═O,C═S, or a C═N at a first carbon atom, and: a C═O or a C═N attached to acarbon atom at least two carbon atoms away from the first carbon atom;or an O, S, or N as a member of the ring at least two positions awayfrom the first carbon atom; and

[0054] (1)-(4) refer to the respective double-bonded carbon atoms.

[0055] Examples of particularly preferred structures B of Formula IIIwhere EWG and R₂ form a cyclic electron-withdrawing unit include thefollowing:

[0056] where R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl.

[0057] Formula IV:

[0058] where:

[0059] each R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl;

[0060] EWG is a non-aromatic electron-withdrawing group such as acarbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group; and

[0061] (1)-(4) refer to the respective double-bonded carbon atoms.

[0062] In another embodiment the light attenuating compounds include anEWG coupled with an EDG across a conjugated double bond system. Anexample of this structure is shown in Formula V.

[0063] Formula V:

[0064] where:

[0065] each R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl;

[0066] EDG is an electron-donating group such as H₃CO—, —OH, orR_(x)R_(y),N—, where each of R_(x) and R_(y) is non-aromatic and mayindividually be hydrogen, or an acyclic (preferably C₁-C₂) or cyclic(preferably C₅-C₆) alkyl or heteroalkyl;

[0067] in structure A, where EWG and R₂ do not form a cyclic unit:

[0068] EWG is a non-aromatic electron-withdrawing group (other thancyano groups) such as a carbonyl, imino, carboxylic acid, carboxylicester, carboxamido, carboximido, or sulfonyl group, and R₂ isnon-aromatic and may be hydrogen, an acyclic (preferably C₁-C₄ branchedor unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or anelectron-withdrawing group such as a carbonyl, imino, cyano, carboxylicacid, carboxylic ester, carboxamido, carboximido, or sulfonyl group; or

[0069] EWG is a cyano group, and R₂ is non-aromatic and may be hydrogen,or an acyclic (preferably C₁-C₄ branched or unbranched) or cyclic(preferably C₅-C₆) alkyl or heteroalkyl;

[0070] in structure B, where EWG and R₂ form a cyclicelectron-withdrawing unit, the cyclic unit preferably comprises a C═O,C═S, or a C═N at a first carbon atom, and: a C═O or a C═N attached to acarbon atom at least two carbon atoms away from the first carbon atom;or an O, S, or N as a member of the ring at least two positions awayfrom the first carbon atom; and

[0071] (1)-(4) refer to the respective double-bonded carbon atoms.

[0072] Examples of particularly preferred structures B of Formula Vwhere EWG and R₂ form a cyclic electron-withdrawing unit include thefollowing:

[0073] where R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl.

[0074] Of course, those skilled in the art will appreciate that lightattenuating compounds in accordance with the invention can includemixtures of the foregoing Formulas I-V in the particularphotolithographic composition.

[0075] In another embodiment, the foregoing structures can be dimerizedto form new compositions which are preferably incorporated intophotolithographic compositions to absorb light, thus minimizing oreliminating the reflectance from the substrate. These dimerizedstructures are shown in Formulas VI-VIII.

[0076] Formulas VI:

[0077] where:

[0078] each R₁ is non-aromatic and may individually be hydrogen, or anX's acyclic (preferably C₁-C₄ branched or unbranched) or cyclic(preferably C₅-C₆) alkyl or heteroalkyl;

[0079] each R₃ may individually be R₁ or

[0080] where each R₁ is non-aromatic and may individually be hydrogen,or an acyclic (preferably C₁-C₄ branched or unbranched) or cyclic(preferably C₅-C₆) alkyl or heteroalkyl, and where the (*) representsthe double-bonded carbon atom (1) or (4);

[0081] each EWG is a non-aromatic electron-withdrawing group such as acarbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group;

[0082] each R₂ is non-aromatic and may individually be hydrogen, anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl, or an electron- withdrawing group such as acarbonyl, imino, cyano, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group;

[0083] R₄ is a divalent, non-aromatic-containing bridging group such as—(CH₂)_(n)—, dimethylenecyclohexyl (—CH₂-C₆H₄-CH₂-), —CH₂CH₂—O—CH₂CH₂—,or other acyclic (preferably C₁-C₄, branched or unbranched) or cyclic(preferably C₅-C₆) alkyls or heteroalkyls; and

[0084] (1)-(4) refer to the respective double-bonded carbon atoms.

[0085] Formulas VII:

[0086] where:

[0087] each R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl;

[0088] each R₂ is non-aromatic and may individually be hydrogen, anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl, or an electron- withdrawing group such as acarbonyl, imino, cyano, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group;

[0089] each R₃ may individually be EDG, or

[0090] where each R₁is non-aromatic and may individually be hydrogen, oran acyclic (preferably C₁-C₄ branched or unbranched) or cyclic(preferably C₅-C₆) alkyl or heteroalkyl; EDG is an electron-donatinggroup such as H₃CO—, —OH, or R_(x)R_(y)N—, where each of R_(x) and R_(y)is non-aromatic and may individually be hydrogen, or an acyclic(preferably C₁-C₂) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl;and where the (*) represents the double-bonded carbon atom (1) or (4);

[0091] R₄ is a divalent, non-aromatic-containing bridging group such as—(CH₂)_(n)—, dimethylenecyclohexyl (—CH₂-C₆H₄-CH₂—), —CH₂CH₂—O—CH₂CH₂—,or other acyclic (preferably C₁-C₄, branched or unbranched) or cyclic(preferably C₅-C₆) alkyls or heteroalkyls;

[0092] each EWG is a non-aromatic electron-withdrawing group such as acarbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group; and

[0093] (1)-(4) refer to the respective double-bonded carbon atoms.

[0094] Formula VIII:

[0095] where:

[0096] each R₁ is non-aromatic and may individually be hydrogen, or anacyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl;

[0097] where each R₃ may individually be an EWG,

[0098] in structure A of Formula VIII, in situations where R₃ is an EWGor structure C (i.e., EWG and R₂ do not form a cycic unit):

[0099] each EWG is a non-aromatic electron-withdrawing group (other thancyano groups) such as a carbonyl, imino, carboxylic acid, carboxylicester, carboxamido, carboximido, or sulfonyl group, and each R₂ isnon-aromatic and may individually be hydrogen, an acyclic (preferablyC₁-C₄ branched or unbranched) or cyclic (preferably C₅-C₆) alkyl orheteroalkyl, or an electron-withdrawing group such as a carbonyl, imino,carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonylgroup; or

[0100] EWG is a cyano group, and each R₂ is non-aromatic and mayindividually be hydrogen, or an acyclic (preferably C₁-C₄ branched orunbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl;

[0101] in structure B of Formula VIII, and in structure A of FormulaVIII where R₃ is structure D (i.e., in situations where EWG and R₂ forma cyclic electron-withdrawing unit), the cyclic unit preferablycomprises a C═O, C═S, or a C═N at a first carbon atom, and: a C═O or aC═N attached to a carbon atom at least two carbon atoms away from thefirst carbon atom; or an O, S, or N as a member of the ring at least twopositions away from the first carbon atom; and

[0102] each EDG is an electron-donating group such as —O—, —S—, or

[0103] —R₅N—, where R₅ is hydrogen or an acyclic (preferably C₁-C₂) orcyclic (preferably C₅-C₆) alkyl or heteroalkyl;

[0104] R₄ is a divalent, non-aromatic-containing bridging group such as—(CH₂)_(n)—, dimethylenecyclohexyl (—CH₂-C₆H₄-CH₂—), —CH₂CH₂—O—CH₂CH₂—,or other acyclic (preferably C₁-C₄, branched or unbranched) or cyclic(preferably C₅-C₆) alkyls or heteroalkyls; and

[0105] (1)-(4) refer to the respective double-bonded carbon atoms.

[0106] Examples of particularly preferred structures A of Formula VIIIwhere R₃ is structure D (i.e., so that EWG and R₂ form a cyclicelectron-withdrawing unit) include the following:

[0107] where each R₁ is non-aromatic and may individually be hydrogen,an acyclic (preferably C₁-C₄ branched or unbranched) or cyclic(preferably C₅-C₆) alkyl or heteroalkyl, and each R₂ is non-aromatic andmay individually be hydrogen, an acyclic (preferably C₁-C₄ branched orunbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or anelectron-withdrawing group such as a carbonyl, imino, carboxylic acid,carboxylic ester, carboxamido, carboximido, or sulfonyl group.

[0108] Examples of particularly preferred structures B of Formula VIIIwhere EWG and R₂ form a cyclic electron-withdrawing unit include thefollowing:

[0109] where R₁ is non-aromatic and may individually be hydrogen,acyclic (preferably C₁-C₄ branched or unbranched) or cyclic (preferablyC₅-C₆) alkyl or heteroalkyl, and each R₂ is non-aromatic and mayindividually be hydrogen, an acyclic (preferably C₁-C₄ branched orunbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or anelectron-withdrawing group such as a carbonyl, imino, carboxylic acid,carboxylic ester, carboxamido, carboximido, or sulfonyl group.

[0110] In another embodiment, a light attenuating compound is attachedto a polymer binder (either directly to the backbone or via a linkageunit) via an EWG. A specific example of one such structure is shown inFormula IX.

[0111] Formula IX

[0112] where EWG is a non-aromatic electron-withdrawing group such as acarbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group, and each R₁ may individually be hydrogenor an alkyl group (and preferably a methyl group).

[0113] One preferred structure of Formula IX wherein the EWG (a carboxylgroup) is directly attached to a polymer backbone as shown below.

[0114] In another embodiment, two R₁ substituents on a moiety of thelight attenuating compound form a cyclic structure such as those shownin Formulas X and XI.

[0115] where:

[0116] R₂ is non-aromatic and may individually be hydrogen, an acyclic(preferably C₁-C₄ branched or unbranched) or cyclic (preferably C₅-C₆)alkyl or heteroalkyl, or an electron-withdrawing group such as acarbonyl, imino, cyano, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group; and EWG is a non-aromaticelectron-withdrawing group such as a carbonyl, cyano, imino, carboxylicacid, carboxylic ester, carboxamido, carboximido, or sulfonyl group.

[0117] where:

[0118] R₂ is non-aromatic and may individually be hydrogen, an acyclic(preferably C₁-C₄ branched or unbranched) or cyclic (preferably C₅-C₆)alkyl or heteroalkyl, or an electron-withdrawing group such as acarbonyl, imino, cyano, carboxylic acid, carboxylic ester, carboxamido,carboximido, or sulfonyl group; and EWG is a non-aromatic electron-withdrawing group such as a carbonyl, cyano, imino, carboxylic acid,carboxylic ester, carboxamido, carboximido, or sulfonyl group.

[0119] In yet another embodiment, the disclosed Formulas can be joinedto one another to form a polymeric structure for use in aphotolithographic composition without the need for an additional polymerbinder. That is, the polymerized structures would act as the polymerbinder as well as the light absorbing compound. The structures ofFormulas I-XI can by polymerized in a linear fashion by creatingnon-conjugated, non-aromatic linkages between two of the functionalgroups as shown in the table below. Formula Linkages Between: I R₁-R₁;R₁-R₂; R₁-EWG; and R₂-EWG II R₁-EDG; R₁-EWG; R₁-R₂; EDG-EWG; R₂-EDG; andR₂-EWG III R₁-R₁; R₁-R₂; R₁-EWG; and R₂-EWG IV R₁-R₁; R₁-EWG; andEWG-EWG V R₁-EDG; R₁-EWG; R₁-R₂; EDG-EWG; R₂-EWG; and R₂-EWG VI R₁′-R₂″and R₁′-R₁″ VII R₁′-R₂″; R₁′-R₁″; R₁′-EDG″; R₂′-EDG″; and EDG′-EDG″ VIIIR₁′-R₂″; R₁′-R₁″; R₁-EWG″; R₂′-EWG″; and EWG′-EWG″

[0120] Linkage units could be utilized between the structures to formthe above-described linkages. Suitable linkage units include a moietyselected from the group consisting of alkyls, acyclic heteroalkyls,non-aromatic cyclic alkyls, and non-aromatic cyclic heteroalkyls.

[0121] As indicated previously, the light attenuating compound can beattached to the polymer binder backbone or to a functional group orlinkage unit which is, in turn, attached to the polymer backbone.Structures E and F below illustrate these attachments. In structure E, a365 nm dienyl dye having an amino electron-donating group is bonded to apolymer binder via a hydroxypropyl linking group. The dye is attached bya carboxylic ester electron-withdrawing group. In structure F, the aminoelectron-donating group is functionalized with two hydroxyethylsubstituents which are reacted with a diisocyanate to form apolyurethane backbone.

[0122] When used in reference to Formulas I-XI, the term “compounds” isintended to refer to the actual compound represented in the particularFormula, as well as all functional olefinic and/or diolefinic moietiesthereof. For example, the “compound of structure A of Formula I,” refersto the structure A shown in Formula I above as well as the structure:

[0123] where “M” is a compound to which R′ is bonded. Thus, “compound ofstructure A of Formula I” would include those moieties where any of theconstituents (i.e., any of the R groups or the EWG) are bonded toanother compound.

[0124] Also, as used herein, “cyclic” is intended to refer to any group,compound, or moiety which includes a cyclic group as part of itsstructure. Thus, cyclic would include groups such as methylenecyclohexyl(—CH₂-C₆H₅) and ethylenecyclohexyl.

[0125] The following table sets forth preferred compounds which fallinto the classes described above with respect to Formulas I-XIII. ClassPreferred Substituents Acyclic Alkyls methyl, ethyl, propyl, andisopropyl Cyclic Alkyls cyclopentyl and cyclohexyl Acyclic Heteroalkylsmethoxyethyl, ethoxyethyl, methoxypropyl, chloroethyl, and1,1,1-trifluoroethyl Cyclic Heteroalkyls tetrahydrofurfuryl,methylenecyclohexyl (—CH₂—C₆H₅), and ethylenecyclohexyl EWG's Having—CO—CH₃, —CO—CH₂CH₃, and Carbonyl Groups —CO—CH₂(CH₃)₂ EWG's Having—CO—O—CH₃, —CO—O—CH₂CH₃, and Carboxyl Groups —CO—O—CH₂—CH(OH)—CH₂—O—EWG's Having —CO—NH—CH₂—CH₂—OH and Carboxamido Groups —CO—NH—CH₂—CH₂—O—EWG's Having —SO₂—CH₃ and —SO₂—CH₂CH₃ Sulfonyl Groups EDG's Having anH₃C—O—, H₃CCH₂—O—, —CH₂CH₂—O—, Alkoxy Group and R₁-O—, wherein R₁ isnon-aromatic and may individually be hydrogen, or an acyclic (preferablyC₁-C₄ branched or unbranched) or cyclic (preferably C₅-C₆) alkyl orheteroalkyl EDG's Having an (H₃C)₂N—, (H₃CCH₂)₂N—, R_(X)R_(Y)N Group(—O—CH₂CH₂)₂N—, and

EXAMPLE

[0126] The following example sets forth preferred methods in accordancewith the invention. It is to be understood, however, that this exampleis provided by way of illustration and nothing therein should be takenas a limitation upon the overall scope of the invention.

[0127] Poly(glycidyl methacrylate) was reacted with 2,4-hexadienoic acid(a non-aromatic, deep ultraviolet chromophore) at 100-1 10° C. for 24hours with a benzyltriethylammonium chloride catalyst to form a solutionof the dye-attached binder shown in Scheme A.

[0128] The resulting polymer binder was combined in solution (with1-methoxy-2-propanol and ethyl lactate as the solvents) with aglycouril-formaldehyde cross-linking agent and an acid catalyst(p-toluenesulfonic acid) to form a BARC composition. The concentrationsof the various compounds utilized in the composition were as follows:Compounds Parts by Weight^(a) Polymer Solution 14.52 Cross-Linking Agent0.66 p-toluenesulfonic acid 0.06 1-methoxy-2-propanol 42.38 ethyllactate 42.38

[0129] The composition was spin coated onto a silicon wafer at 1500 rpmfor 60 seconds followed by a hotplate bake at 175° C. for 60 seconds toform a BARC layer with a film optical density at 248 nm of 4.83/micron.The coating was then plasma etched in a commercial wafer etching toolusing a mixture of HBr and O₂ as the etchant gas. The etch rate of thecoating was 5815 Å/minute.

[0130] For comparison purposes, the etch rate of a BARC composition(DUV-42 for use in 248 nm photolithographic processes, available fromBrewer Science, Inc., Rolla, Mo.) was determined. The binder in DUV-42is a copolymer of glycidyl methacrylate and 2-hydroxypropyl methacrylatein which the glycidyl groups have been reacted with9-anthracenecarboxylic acid (9-ACA) to form a dye-attached binder withhigh light absorbency at 248 nm. The DUV-42 was applied to a siliconwafer and processed following the procedures set forth above withrespect to the inventive composition. The etch rate of the DUV-42 was3218 Å/minute. Thus, the composition utilizing a light attenuatingcompound according to the invention etched 1.8 times faster than theprior art product. The comparatively low plasma etch rate of the DUV-42was a result of the high aromatic ring content of the 9-ACA.

We claim:
 1. In a curable composition for use during microlithographicprocesses, said composition comprising a polymer binder dissolved in asolvent system, the improvement which comprises a non-aromatic, lightattenuating compound which absorbs light at wavelengths of less thanabout 300 nm in said composition.
 2. The composition of claim 1, whereinsaid light attenuating compound is bonded to the polymer binder.
 3. Thecomposition of claim 1, wherein the polymer binder comprises a backbone,and said light attenuating compound is bonded to said backbone.
 4. Thecomposition of claim 1, wherein said light attenuating compound isbonded to a linkage unit and said linkage unit is bonded to the polymerbinder.
 5. The composition of claim 4, wherein said linkage unitcomprises a moiety selected from the group consisting of cyclic alkyls,acyclic alkyls, acyclic heteroalkyls, and cyclic heteroalkyls.
 6. Thecomposition of claim 1, wherein said light attenuating compound includesa moiety selected from the group consisting of COOH, OH, CONH₂, CONHR′,CH₂X, and mixtures thereof, wherein R′ is selected from the groupconsisting of hydrogen, alkyls, and heteroalkyls, and wherein X is ahalogen.
 7. The composition of claim 1, wherein after curing, saidcomposition has an etch rate of at least about 4000 Å/minute whenutilizing an etchant gas comprising a mixture of HBr and O₂.
 8. Thecomposition of claim 1, wherein said light attenuating compoundcomprises an olefinic moiety including carbon atoms C₁ and C₂double-bonded to one another, and an EWG bonded to carbon atom C₁. 9.The composition of claim 8, wherein the EWG includes a moiety selectedfrom the group consisting of carbonyl, carboxyl, carboxamido, sulfonyl,and non-aromatic heterocyclic groups.
 10. The composition of claim 8,said light attenuating compound comprising a diolefin, including carbonatoms C₃ and C₄ double-bonded to one another, and wherein C₃ is bondedto C₂ so as to form conjugated double bonds.
 11. The composition ofclaim 10, further including an EDG bonded to C₄.
 12. The composition ofclaim 11, wherein the EDG includes a moiety selected from the groupconsisting of H₃CO, OH, and R₁—O—, wherein R₁ is non-aromatic and isselected from the group consisting of hydrogen, acyclic and cyclicalkyls, and heteroalkyls.
 13. The composition of claim 10, furtherincluding a second EWG, said second EWG being bonded to C₄.
 14. Thecomposition of claim 13, wherein the second EWG includes a moietyselected from the group consisting of carbonyl, carboxyl, carboxamido,sulfonyl, and non-aromatic heterocyclic groups.